Service Example

This section discusses a very simple Service function called simple_service. All this function does is send a message in response to a client request. The message is initialized by the init_simple_service function during server initialization.

For a more complex example, see the file service.c in the examples directory, which is discussed in More Complex Service Example.

Installing the Example

To load the shared object containing your functions, add the following line in the Init section of the magnus.conf file:

Init fn=load-modules shlib=yourlibrary funcs=simple-service-init,simple-service

To call the function, simple-service-init function for initializing the message representing the generated output, add the following line to the Init section in magnus.conf. (This line must come after the one that loads the library containing simple-service-init.)

Init fn=simple-service-init
 generated-output="<H1>Generated output msg</H1>"

To execute the custom SAF during the request-response process for some object, add the following line to that object in the obj.conf file:

Service type="text/html" fn=simple-service

The type="text/html" argument indicates that this function is invoked during the Service stage only if the content-type has been set to text/html.

Source Code

#include <nsapi.h>
static char *simple_msg = "default customized content";
/* This is the initialization function.
 * It gets the value of the generated-output parameter
 * specified in the Init directive in magnus.conf
*/
NSAPI_PUBLIC int init-simple-service(pblock *pb, Session *sn,
 Request *rq)
{
    /* Get the message from the parameter in the directive in
      * magnus.conf
     */
    simple_msg = pblock_findval("generated-output", pb);    
    return REQ_PROCEED;
}
/* This is the customized Service SAF.
 * It sends the "generated-output" message to the client.
*/
NSAPI_PUBLIC int simple-service(pblock *pb, Session *sn, Request *rq)
 {    
     int return_value;
    char msg_length[8];    
    /* Use the protocol_status function to set the status of the
     * response before calling protocol_start_response.
    */
    protocol_status(sn, rq, PROTOCOL_OK, NULL);
    /* Although we would expect the ObjectType stage to
     * set the content-type, set it here just to be
    * completely sure that it gets set to text/html.
    */
    param_free(pblock_remove("content-type", rq->srvhdrs));
    pblock_nvinsert("content-type", "text/html", rq->srvhdrs);
    /* If you want to use keepalive, need to set content-length header.    
    * The util_itoa function converts a specified integer to a
     * string, and returns the length of the string. Use this
     * function to create a textual representation of a number.
    */
    util_itoa(strlen(simple_msg), msg_length);
    pblock_nvinsert("content-length", msg_length, rq->srvhdrs);
    /* Send the headers to the client*/
    return_value = protocol_start_response(sn, rq);
     if (return_value == REQ_NOACTION) {
         /* HTTP HEAD instead of GET */
         return REQ_PROCEED;
     }
    /* Write the output using net_write*/
    return_value = net_write(sn->csd, simple_msg,
         strlen(simple_msg));
     if (return_value == IO_ERROR) {
         return REQ_EXIT;
     }
    return REQ_PROCEED;
}

More Complex Service Example

The send-images function is a custom SAF that replaces the doit.cgi demonstration available on the iPlanet home pages. When a file is accessed as /dir1/dir2/something.picgroup, the send-images function checks if the file is being accessed by a Mozilla/1.1 browser. If not, it sends a short error message. The file something.picgroup contains a list of lines, each of which specifies a file name followed by a content-type (for example, one.gif image/gif).

To load the shared object containing your function, add the following line at the beginning of the magnus.conf file:

Init fn=load-modules shlib=yourlibrary funcs=send-images

Also, add the following line to the mime.types file:

type=magnus-internal/picgroup exts=picgroup

To execute the custom SAF during the request-response process for some object, add the following line to that object in the obj.conf file (send-images takes an optional parameter, delay, which is not used for this example):

Service method=(GET|HEAD) type=magnus-internal/picgroup fn=send-images

The source code is in service.c in the nsapi/examples/ or plugins/nsapi/examples subdirectory within the server root directory.